There is considerable commercial interest in nano-particles and suspensions thereof. Graphene in particular has shown promise due to its interesting electronic, thermal and mechanical properties. Graphene comprises sheets of an extended carbocyclic aromatic network and may be regarded as an exfoliated graphite. The use of graphene in commercial applications has however been limited due to the relatively small amounts that are produced using conventional techniques. Also, graphene sheets have a strong tendency to aggregate even in suspension. This problem increases with increasing concentration of the graphene in the suspension. Similar problems pertain to other materials which consist of platelets or sheets, such as talc, clays etc.
Aggregation of platelets or sheets in suspension may be inhibited by use of surfactants. However many surfactants can desorb from the surface of exfoliated sheets, leading to aggregation and possibly instability of the suspension. Furthermore, if the exfoliated sheets are dried, resuspension is generally difficult due to reaggregation. Resuspended materials may require sonication in order to re-exfoliate the material.